Insulators with helical fin and tapered body



Nov; 12, 1963 J. M. moussou INSULATORS win! HELICAL FIN AND TAPERED BODYFiled July 1'7, 1961 Fig, 1 PRIOR ART United States Patent Ofi iceClaims priority, application France July 19, 196i 3 Claims. (Ql. 174211)4 The present invention relates to an improvement in insulators withhelicoidal fins for high-tension lines or apparatus, with a view toimproving the operating characteristics of insulators during rain,especially in the case of a. polluted atmosphere. It consists inconstructing the insulator in such manner that the edge of at least oneof the spirals constituting the helicoidal fin passes beyond the edge ofthe lower adjacent spiral.

The construction and the scope of the invention will be betterunderstood by reference to the accompanying drawings, in which:

FIG. 1 represents a view in profile and partly IIICIOSS- section of aninsulator with a heli-coidal fin of known type tion in profile andpartly in cross-section.

The insulator of FIG. 1 comprises essentially a barrel body .1 ofinsulating material, ceramic for example, on which is wound a helicoidalfin 2 defined by spirals 3. Two metal fittings 4 are sealed into theinterior of the body 1. The section through a diametral plane of thisinsulator, shown at the left-hand side of FIG. .1, shows the profile ofthe spiral, characterized in the present example by two double bosses 5,6' and 7, 8. Thus, two helicoidal channels are formed which collect andconduct away the rain water, ensuring an eifective washing of thisportion ofthe fin. It has however been found that for a certaininclination of the insulator with respect to the profile of the fin, thecollected water may overflow and drip on to the spiral below instead ofrunning down the channels. When the spirals are suificiently closetogether, they may thus be short-circuited, which may give rise to aflash-over.

It is of cotu'se possible to increase the pitch of the helicoidal fin byspacing the spirals further apart, but the line of leakage is therebydiminished and the protection of the body against power arcs resultingfrom the presence of close spirals is reduced.

In accordance with'one form of the invention, it is possible to arrangetwo or more helicoidal fins in such manner that at least one has alength of spiral section less than that of the other or others. In thisway, approximately the same line of leakage is maintained, measuredalong a generator line, while removing a certain number of successivespirals ttrom the danger of short-circuit by streams of water. On theother hand, the line of leakage measured along the development of thehelix is reduced by 1/ 2, 1/3 or 1/ n, depending on the number ofhelixes adopted, and since these diiferent helixes are parallel, theinsulation along the helix has its value divided byd, 9 or 11 g Thissolution is acceptable in certain cases, when the effects of pollutionare limited, but it can no longer be FIGS. 2, 3 and 4 show differentforms of the invenspiral extends beyond the edge or" the spiral below.'Account is talren of the reduction in diameter of the body towards thebottom by providing a metal fitting 12 sealed internally in the upperportion and a metal fitting 13 sealed externally in the lower portion.

According to the embodiment shown in FIG. 3, the body of the insulator20 is not trusto-conical as in FIG. 2, but has a diameter whichdecreases and increases periodically from the upper portion of theinsulator to the lower portion. A helix 21 is wound on this body.Although in the construction described, the diameter of the body variesin a periodic and uniform manner along the axis of the insulator, it isclear that this condition is not necessary, and that other laws ofvariation may be chosen. In any event, it will be auadvantage that theextremities of the body in which the metal fittings 22 are sealed, arelocated in a zone of maximum diameter.

In accordance with the embodiment shown in FIG. 4, the body of theinsulator 31) is cylindrical, but the length of the profile of thespiral of the helicoidal fin 31 varies periodically between two limitsalong the longitudinal axis, in order to avoid successive spirals fromhaving the same length of profile along any particular generator line.It is essential that the period of variation of the length of profile ofthe spiral should not correspond to a pitch or a whole multiple of apitch of the helix.

The fabrication of the insulators in accordance with FIG. 2, 3 or 4,does not present any difficulty. In the the period desired.

case of FIGS. 2 and 3, it is only necessary to give the tool which cutsthe helix in the blank, a radial movement, the law or" which is combinedin a simple manner with the axial movement.

In the case of the einbodiment'raccordin-g to FIG. 4,

it is sufficient to arrange, after a first tool which has cut a regularhelix, a second tool given a radial movement combined with the axialmovement in accordance with In this case, naturally, the profile of thespiral should be such that the shortening of the length does notinterfere with the collection and the flowgang-away of the water throughthe helicoidal channels t is quite clear that the constructionsdescribed are only given by way of example and without any limitation,certain details of some being even applicable to the others, whileremaining Within the scope of the invention.

What I claim is:

l. A solid core suspension insulator comprising an insulator body whosediameter varies along the axis of the insulator, said body beingprovided with at least one peripheral spiral flange disposed extendingaxially on said body from one end to the other thereof, such that theradial depth of said flange is constant throughout its entire length andsaid body having a metal fitting sealed at each end thereof, at leastone of said fittings being internally sealed.

2. A solid core suspension insulator comprising an elongatedfrustro-conical insulator body, said body being provided with at leastone peripheral spiral flange disposed extending axially on said bodyirom one end to the other thereof such that the radial depth of saidflange is constant throughout its entire length, a first metal fittingsealed internally in the uppermost portion of said body and a secondmetal fitting sealed externally on the lowermost portion or" said body.

3. A solid core suspension insulator comprising an elongated insulatorbody who-se diameter varies in a periodic manner along the axis of theinsulator, said body being provided with at least one peripheral spiralflange disposed extending axially on said body from one end to the otherthereof, such that the radial depth of said flange is conmy 3? V stantthmughsut its entire length, a first metal fitting 1,942,284 stza-lvsclinternally at one end of said bsdy and a second 2,175,336 metal fittingsealed internally at the: :othsr end of said body.

t 5 391,017 References Cited in the file of this patent 349,410 Q" )1UNITED STATES PATENTS fi; 1,811,530 Baum June 23, 1931 845:498 1,870,141Regerbis et a1 Aug. 2, 1932 Halton Jan. 2, 1934 Austin Oct. 10, 1939FOREIGN :fPAT EN TS Germany M21124, 1924 Italy June 15, 1937 France 2Apr. 27, 1959 France Jan. 22, 19 4-2 Great Britain Aug. 24, 1960

1. A SOLID CORE SUSPENSION INSULATOR COMPRISING AN INSULATOR BODY WHOSEDIAMETER VARIES ALONG THE AXIS OF THE INSULATOR, SAID BODY BEINGPROVIDED WITH AT LEAST ONE PERIPHERAL SPIRAL FLANGE DISPOSED EXTENDINGAXIALLY ON SAID BODY FROM ONE END TO THE OTHER THEREOF, SUCH THAT THERADIAL DEPTH OF SAID FLANGE IS CONSTANT THROUGHOUT ITS ENTIRE LENGTH ANDSAID BODY HAVING A METAL FITTING SEALED AT EACH END THEREOF, AT LEASTONE OF SAID FITTINGS BEING INTERNALLY SEALED.